S. African black women taking jobs alongside whites

Constance Nkosi exudes hope.

In the next two weeks she expects ''with fingers crossed'' to become the first black woman in South Africa to be awarded a masters degree in business administration. Meanwhile, she is settling in to her new job as advertising manager for a large clothing manufacturer.

''I'm constantly improving myself and I feel the sky is the limit,'' says the smartly dressed mother of two.

Such optimism is not misplaced. At least a few black women in South Africa are quietly making mincemeat of job barriers that made them servants to white employers and their own chauvinistic husbands.

Blacks still face huge obstacles in making any progress in their jobs here. Having few political rights, they are relegated by the government to providing mainly a cheap and tightly controlled labor pool for the white-run economy.

For South Africa's black women, combatting such racism, as well as sexism, is expected to require a long, hard battle. Those making headway, like Mrs. Nkosi, represent a very small group.

But the headway they are making is so dramatic as to warrant notice, says Truida Prekel of the University of South Africa. Her research shows that black women are advancing into the professions, industry, and white-collar job fields at a faster rate than white women or black men. (The precentage increase of black women in those job areas has been well ahead of the increases by the other groups.)

Mrs. Prekel finds the rate of advancement particularly impressive since black women ''are exposed to discrimination both because they are women and because they are black.''

Opportunities exist for black women because of a changing economic scene in South Africa. A desperate need for skilled labor has forced the government to relax apartheid in the job sphere to some degree - and to begin to promote the hiring and advancement of blacks in some positions previously reserved for whites. But Mrs. Prekel says the black women themselves deserve most of the credit.

''They are self-disciplined, independent, and hard working,'' she says.

The disadvantaged position of black women in South African society may have prepared them exceptionally well for success in the job field, she adds.

South Africa's race laws not only separate different race groups, but also have encouraged separation within black families. Black women are used to fending for themselves; many must fill the role of mother, father, and part-time provider when their husbands take jobs as migrant workers. The large number of black women working as domestic servants in white homes know family separation as a way of life.

This background, Mrs. Prekel explains, has taught black women to cope well with whatever family disruptions may result from career advancement.

Connie Pretorius crashed a job barrier six years ago when she became South Africa's first black woman clinical psychologist. She is a member of the predominantly white teaching staff of the Medical University of Southern Africa.

Mrs. Pretorius figures one of the root causes of black women's growing success in the economic sphere is the high value placed on education.

''The only thing most black parents can offer their children is an education, '' she says. ''They see it as the only source of real security that they can pass along, since they usually have no financial inheritance.''

Mrs. Pretorius says black women do not feel they have to choose between having children or having a career. Extended families are common among blacks; children often are cared for by grandparents.

The impact of black women moving into jobs where they have white peers or subordinates can be profound. Stereotypes are challenged on both sides of the color line.

One black woman working alongside whites says frankly that she grew up ''hating the white man.'' Work experiences have endorsed and challenged that view.

This woman's success in the ''white'' world has also caused some friction at home. Recognizing the value of a good education, which she feels was denied her in black public schools, she wants her children educated in a private, mixed-race school. Her husband resists, fearing the children will be exposed to white racism too early.

Mrs. Pretorius says she has encountered no hostility from white colleagues. But she says blacks are so cautious that even when black and white work side by side, ''There is never complete acceptance or total trust.''

Nearly half of working black women here remain in traditional farm or domestic jobs. But their numbers in the professions have doubled since 1969, with the greatest surge coming in relatively new fields for blacks such as university professors and technical assistants. Black women make up nearly 70 percent of all black professionals here.